Elastomeric fluoropolymers (i.e. fluoroelastomers) exhibit excellent resistance to the effects of heat, weather, oil, solvents and chemicals. Such materials are commercially available and are most commonly copolymers of vinylidene fluoride (VF2) with hexafluoropropylene (HFP) and, optionally, tetrafluoroethylene (TFE). Other known fluoroelastomers include copolymers of TFE with a perfluoro(alkyl vinyl ether) such as perfluoro(methyl vinyl ether) (PMVE), copolymers of TFE with propylene (P) and, optionally VF2, and copolymers of ethylene (E) with TFE and PMVE. Often, these fluoroelastomers also contain copolymerized units of a cure site monomer to facilitate vulcanization. While these copolymers have many desirable properties, including low compression set and excellent processability, their low temperature flexibility is not adequate for some end use applications. One particularly desirable improvement would be a reduction in glass transition temperature (Tg) with an accompanying extension of service temperature to lower temperatures. Tg is often used as an indicator of low temperature flexibility because polymers having low glass transition temperatures maintain elastomeric properties at low temperatures.
Semi-crystalline and crystalline thermoplastic fluoropolymers (i.e. fluoroplastics) include homopolymers (e.g. polytetrafluoroethylene or polyvinylidene fluoride) or copolymers of TFE or VF2 containing up to 20 wt. % of a second (different) fluoromonomer, a hydrocarbon olefin or a combination of the latter. Such copolymers include, but are not limited to THV, FEP and PFA. While these polymers have many desirable properties, in some applications, improved green strength would be beneficial.